@monstermann/fn/dist/array/groupBy.d.ts

A utility library for TypeScript.

//#region src/array/groupBy.d.ts
/**
 * `groupBy(array, grouper, transform?)`
 *
 * Groups elements in `array` by the result of calling `grouper` function on each element, optionally transforming each element with `transform`, returning an object with keys as group values and values as arrays of elements.
 *
 * ```ts
 * groupBy(
 *     [1, 2, 3, 4],
 *     (x) => (x % 2 === 0 ? "even" : "odd"),
 *     (x) => x * 10,
 * ); // { even: [20, 40], odd: [10, 30] }
 * ```
 *
 * ```ts
 * pipe(
 *     [1, 2, 3, 4],
 *     groupBy(
 *         (x) => (x % 2 === 0 ? "even" : "odd"),
 *         (x) => x * 10,
 *     ),
 * ); // { even: [20, 40], odd: [10, 30] }
 * ```
 */
declare const groupBy: {
  <T extends object, U extends PropertyKey, V>(target: readonly T[], by: (value: NoInfer<T>, idx: number, target: readonly NoInfer<T>[]) => U, transform: (value: NoInfer<T>, key: U, idx: number, target: readonly NoInfer<T>[]) => V): Record<U, V[]>;
  <T extends object, U extends PropertyKey>(target: readonly T[], by: (value: NoInfer<T>, idx: number, target: readonly NoInfer<T>[]) => U): Record<U, T[]>;
};
//#endregion
export { groupBy };